Each year in the U.S., over 7,000 pedestrians are killed and over 80,000 are injured when they are hit by a motor vehicle. Adults over age 65 are at especially high risk, in part because of declines in sensory, cognitive, and motor function that accompany aging and affect performance as a pedestrian. Most pedestrian/motor vehicle collision (PMVC) injuries to older adults occur at urban street crossings. The proposed project will attempt to determine the degree to which four environmental features of urban street crossings affect the risk of PMVC injury to older pedestrians. Specifically, it is hypothesized that increased risk is associated with (1) presence of a marked crosswalk. (2) absence of a pedestrian signal, (3) traffic cycle timing that fails to allow for the slower walking speeds of many older adults, and (4) presence of visual obstructions that prevent approaching drivers from seeing pedestrians as they enter the crossing. A case control study will be conducted in Seattle and Tacoma, Washington, and Long Beach, California. The units of study will be street crossings. The 'case crossings' will be street-crossing sites (n=331) at which a pedestrian aged 65 or over suffered a fatal or non-fatal PMVC injury, as identified prospectively over a 4-year period. The 'control crossings' will consist of other sites in the same census block group but at which no such injury occurred (n=662). On-site observations will be made at each case and control crossing on the same day of the week and time of day as the PMVC injury event. These observations will include assessment of (1) the presence, type,, and condition of crosswalk markings; (2) the presence and type of pedestrian signals; (3) traffic signal timing; and (4) presence of parked vehicles, vegetation, or other visual obstructions near the crossing that interferes with drivers' view of pedestrians in it. The on-site observers will also measure physical parameters of the street and characterize vehicular and pedestrian traffic at the crossing. Data analysis will employ statistical methods suitable for matched case- control studies (chiefly conditional logistic regression) to determine the degree to which the four modifiable crossing characteristics are associated with increased PMVC risk to older adults, while controlling for vehicular and pedestrian traffic characteristics and other confounding factors. The findings should be useful to traffic engineers, urban planners, and those involved in health promotion/disease prevention in the elderly. Because of the difficulty of achieving widespread changes in the behavior of drivers and pedestrians, modification of the pedestrian environment offers and attractive alternative way to protect elderly people from injury as they cross the street.